Julian Astle writes about politics and public policy. He previously worked as director of CentreForum, the liberal think tank, and as Political Advisor to Paddy Ashdown when leader of the Liberal Democrats. He is @JulianAstle on Twitter.

If hiring Andy Coulson was Cameron’s worst personnel decision, hiring Ed Llewellyn was his best

John McTernan, a former "enforcer" for Tony Blair who knows a thing or two about political crisis management, is in today’s Telegraph advising David Cameron to toughen up the Downing Street operation by bringing in some “leg-breakers”. His article reads like a Malcolm Tucker soliloquy in The Thick of It, combining his two defining characteristics: cynicism (“Full disclosure is important, but…only of what will eventually come out”) and aggression (“All governments need head kickers”).

The irony, according to McTernan, is that the one person capable of doing “the low politics” necessary to ensure the Prime Minister’s safe passage through the phone hacking scandal is the one man he can no longer call on – Andy Coulson. This leaves him heavily reliant on his Chief of Staff, Ed Llewellyn, who McTernan recognises as a decent man, but believes was too weak in dealing with the Coulson issue.

But the real irony is that McTernan's advice, far from pointing the way for Cameron, serves primarily as a reminder of his past missteps. After all, it was McTernan's suggested mix of bullying and bullshit that Coulson was brought in to provide. That’s what got Cameron into this mess. It is not what will get him out of it.

Which brings me back to Llewellyn, the man McTernan clearly views as the weak link in the Cameron circle.

I first met Ed in 2002 when he and I flew to Sarajevo to work for Paddy Ashdown who had just been appointed High Representative to Bosnia. We sat at adjacent desks for the next three years and became good friends.

Knowing him well, I can confidently say that there is no way he will have “neglected his duty to put the difficult questions to the boss” as McTernan alleges. Not once while I worked with him did he shy away from bringing the boss bad news. Unlike a good many political advisors, Ed was unfailingly polite and respectful, but he never flinched; he was always prepared to tell Ashdown what he least wanted to hear when he knew he needed to hear it. There were plenty of "yes men" in the organisation but Llewellyn wasn’t one of them.

So what are we to make of his email to Assistant Commissioner John Yates, in which he wrote: "I don't think it would really be appropriate for the PM, or anyone else at No 10, to discuss this issue [the Met’s investigation into phone hacking] with you, and would be grateful if it were not raised please"?

The answer is that this was the only response he could (and should) have given to what was a highly inappropriate suggestion: that a senior police officer should provide the prime minister with details of a criminal investigation into the activities of one of his employees. Had Llewellyn taken the opposite decision, the investigation could have been compromised and any subsequent legal proceedings made unsafe, which is precisely why both the Cabinet Secretary and the Permanent Secretary approved the email before it was sent.

Far from providing evidence of Llewellyn’s inadequacies then, this episode highlights his strengths – his judgment and his probity. And in the new post-Coulson, post-Murdoch, post-Malcolm Tucker era we are entering, it is these qualities, rather than an ability to induce fear, that Cameron will need in a Chief of Staff.